The Paired t-Test Involving
Two Related Means

If the variables are paired, then we are interested in the change between
the first set of data and the second. Let one set of variables equal
x , and the other equal y. the difference of a set n
(dn) would equal
xn minus yn :

d = x-y

To conduct a paired t-test of the mean, we need two values: First, the mean
of the differences of all of the pairs, which is easily computed with the
equation. Keep in mind that n equals the number of pairs.